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authorDan Williams <dan.j.williams@intel.com>2018-02-23 11:42:05 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-02-25 11:03:53 +0100
commit43e4f5aeaff2d6604d2c16267c8b15257cf974ea (patch)
tree5459b7f0db9bc92c15ab4fd23074fde5c9a05eef /include/linux
parentc8961332d6da59b8a39998f46831fe7871cd1519 (diff)
vfs, fdtable: Prevent bounds-check bypass via speculative execution
(cherry picked from commit 56c30ba7b348b90484969054d561f711ba196507) 'fd' is a user controlled value that is used as a data dependency to read from the 'fdt->fd' array. In order to avoid potential leaks of kernel memory values, block speculative execution of the instruction stream that could issue reads based on an invalid 'file *' returned from __fcheck_files. Co-developed-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> [jwang: cherry pick to 4.4] Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/fdtable.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 5295535b60c6..a7b7a050bfa8 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -9,6 +9,7 @@
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
+#include <linux/nospec.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/fs.h>
@@ -81,8 +82,10 @@ static inline struct file *__fcheck_files(struct files_struct *files, unsigned i
{
struct fdtable *fdt = rcu_dereference_raw(files->fdt);
- if (fd < fdt->max_fds)
+ if (fd < fdt->max_fds) {
+ fd = array_index_nospec(fd, fdt->max_fds);
return rcu_dereference_raw(fdt->fd[fd]);
+ }
return NULL;
}